Effect of shielding gas and transfer mode on the application of 625 alloy in carbon steel

In this study the effect of shielding gas (Ar, Ar/CO2, Ar/O2 and Ar/He/O2) and transfer mode (short-circuit and pulsed current) in MIG/MAG welding with ER-NiCrMo-3 wire to produce bead-on-plate deposits and root passes in "V" joints of ABNT 1020 steel were analyzed. The most favorable results in root pass welding were obtained with pulsed current, employing a "V" joint with a 90º aperture and Ar+25%CO2 atmosphere. The use of shielding atmospheres with 20% helium and a low percentage of active gas did not produce the expected results, being effective only in bead-on-plate weld deposition. However, it was not very effective to produce satisfactory results in root pass welding. Poor results were obtained in the welding with short-circuit transfer regardless of the used shielding gas, and when an atmosphere of pure argon was used, regardless of the mode of transfer.

Nickel Alloys; 625 Alloys; ER NiCrMo-3; GMAW; Root Welding; Recovery